This Invention relates to tooth positioning appliances, and in particular it relates to an adaptation of such an appliance for the correction of or retention of a correction for overbite or open bite conditions.
In the field of orthodontics, conventional orthodontic devices such as bands or the like are often used for straightening teeth to bring them to a predetermined position of proper or close to proper occlusion. To bring the teeth into a final position of desired orientation in the mouth, the orthodontist will often use a tooth positioner. One type of positioner which is custom made for each individual patient is illustrated in the Kesling U.S. Pat. No. 2,467,432. Another type of positioner which is preformed in a limited number of sizes, and wherein the patient is fitted with the correct one of the limited number of sizes is shown in my Canadian Pat. No. 897,464, issued Apr. 11, 1972.
In the manufacture of both custom and preformed positioners, the present practice is to make the positioners so that as the teeth approach their desired position and the patient occludes his teeth into the positioner, all of the occlusal surfaces of the complete dentition tough the isthmus of the positioner substantially concurrently. A slight variation of this involves a protective feature built into the preformed positioners wherein, in order to compensate for varying free-way spaces (the space between the posterior maxillary and mandibular occlusal surfaces during a person's normal rest position) the positioners were designed such that the occlusal surfaces of the anterior teeth would tough the isthmus of the positioner one half millimeter prior to the occlusal surfaces of the posterior teeth.
While these positioners perform their intended functions satisfactorily, it has been found that they cause increases in vertical overbite, i.e. the excess downward extension of the maxillary anterior teeth over the mandibular anterior teeth, and encourage relapse of corrected overbites. This represents a significant disadvantage since overbite is the most difficult characteristic to treat orthodontically and to retain, and because overbite is probably the most important cause of periodontal degeneration in the adult dentition and cannot be successfully corrected in the adult stage. Clearly then, if overbite could be corrected and properly retained in the growing child, it would be a very significant service to the future health of that child's dentition.
Hence, there exists a need for improvements in the art relating to orthodontic positioners for effectively dealing with overbite problems.